KEY LARGO, Fla.—Two gurgling scuba divers meander over the ocean floor, their motion slow, calculated, and delicate. In unison they rise partway up a towering, tree-shaped rack holding suspended coral fragments. Each gingerly picks a fragment, then descends to place it in the center of a circle surrounded by kneeling divers.
Another pair of divers repeats the procedure, then another. The scene appears mystical and pagan, as if the corals are talismans from the past and future.
These divers are helping the Reef Restoration Foundation. Based in Key Largo, it is one of a burgeoning number of organizations trying to re-forest reefs by tapping the free labor of scuba divers looking to vacation for a cause.
Hard corals — the skeletal homes built by communities of tiny animal polyps — are struggling worldwide. A half-dozen projects are in varying stages of creating repopulation programs by capitalizing on divers who want to pay it forward.
For two days and three dives last June, 10 such vacationers, primarily affiliated with the Scuba Unlimited Dive Shop in Cincinnati, were a case in point.
“This is the first time I have taken a vacation to try to make the world better,” said John Stewart, 47, the owner of a landscape irrigation service in Ohio. He was aboard a dive boat speeding several miles east from the Key Largo coast in preparation for the first plunge.
Steve Allen, a scuba instructor, sat nearby. “This is the essence of why I teach,” Allen said. “Coral restoration gives students something constructive to do with their certification.”
Across the deck, Jennifer Grant, 23, was adjusting equipment straps and testing regulator components that growled to her touch.
“It’s cool to be able to make the world better while still enjoying a dive,” Grant said. “The shame is that so much of the hard coral is dead that the only healthy reefs I have seen are in books.”
Hard corals, not to be confused with their plant-like softer cousins, are the colorful skeleton homes of tiny animals struggling for their lives. Conservation organizations such as the Washington, D.C.-based World Resources Institute estimate 40 percent of hard corals worldwide are dead or dying. Ninety-eight percent of Acroporas — the stag horn and elk horn postcard giants that once studded the Florida Keys and the Caribbean — are gone.
Human fingerprints cover the crime scene. For example, overfishing is depleting the fish stocks that clean suffocating algae from the polyps. Fossil fuel emissions are increasing ocean acidity and the incidence of heat shocks, both coral killers.
Two decades ago, Ken Nedimyer was in the Florida tropical fish and coral trade when he started observing the underwater world slowly dissolving like eggshells in vinegar — which is what an acidic ocean does to the coral skeleton.
“I could not just sit there and do nothing,” recalled Nedimyer, 56, who speaks as passionately of corals as Rachel Carson, the late author of “Silent Spring,” spoke of bird songs. Admirers say Nedimyer, like Carson, exemplifies one person determined to make a difference.
In 2002 he noticed a few transplanted stag horn corals begin to thrive on a reef scraped raw by a grounded ship. Experiments in the wild ultimately persuaded him he could grow stag horns the size of basketballs from fragments no larger than a dog treat. So in 2007 Nedimyer created the Coral Restoration Foundation, which to date has planted 4,000 corals in the upper Keys. His goal is 40,000 corals by 2016.
His critics argue that until you address human misbehavior, restoration will be a waste of effort. Nedimeyer has little patience for such naysaying.
“To those who ask: ‘What if it doesn’t work?’ I reply: ‘So what’s the solution? Do nothing?’ ” Nedimeyer is persuaded there is sufficient diversity in the coral gene pool he mixes and matches in his “nursery” to create a heartier coral.
For big-time assistance, he taps the human gene pool.
Some 975,000 divers annually take scuba vacations in the Keys, according to a 2010 federal survey. Key Largo leads the list. Last year 1,000 of them volunteered for Nedimyer. By the end of this year, the annual total may exceed 1,500 divers.
They hail from dive clubs, scuba shops, and institutions nationwide, including universities, zoos, aquariums — and for two days they included 10 flatlanders from Ohio. Kevin Sommerkamp, a supervisor at the Newport Aquarium in Cincinnati, was one.
“We drove 23 hours in a Dodge Journey to get here because finally I have something to really dive for,” Sommerkamp said. With the boat moored, over the rail he rolled, trailing a stream of air bubbles.
Dive one: From an acre of sand 30 feet deep protrude dozens of 15-foot high, tree-shaped racks. Coral morsels hang like ornaments from the “branches.” The divers, divided into teams, resemble hummingbirds in suspension as they collect the coral and then gently place the fragments in piles below. One hour later, 60 color-tagged, genetically diverse coral fragments are ready for transplanting.
Dive two: It is the same day, later in the afternoon. The group motors three miles from the nursery to Molasses Reef for a health check of corals planted by other teams earlier in the season. The mechanics of planting a coral are simple: scrape a rock clean of algae, then affix the coral stem with underwater putty.
While many of the new corals on Molasses are thriving, a few have broken branches. But it is difficult to concentrate entirely on the repairs. The reef undulates with a plethora of soft fan corals in some of the clearest, fishiest waters in Florida. The views are stunning. And distracting.
Dive three: The next day’s destination is Dry Rocks Reef. After the boat is moored, the captain introduces everyone to a Florida institution. He is Jerry Greenberg, a pioneer underwater photographer for National Geographic Magazine who is in his mid-80s. Greenberg has arrived on his own boat and will serve as the landscape architect, directing coral placement for best effect on one of his favorite Florida reefs.
“Some day my great-granddaughter Shana will be able to celebrate again the glory of corals in Florida,” Greenberg says. Then the octogenarian pops his regulator in his mouth and jumps overboard. Everyone else basically spends the next hour trying to keep up.
Again and again Greenberg points to planting sites and divers obediently respond. Eventually 60 baby stag horns have white putty foundations and a perch for new life in the wild.
The trip home is into a setting sun. An air of work-done-well permeates the group, which occasionally erupts into laughter and song. The passage seems scripted, in need of a final pithy take-home quote. It goes to Sommerkamp:
“Twenty five years from now I want to bring my kid here. And I want to brag: ‘Look what I did!’ ”